1. Field of the Invention
The present invention relates generally to a packaging arrangement for packaging products, such as contact lenses, in packages such as blister packs. More particularly, the subject invention pertains to a packaging arrangement having a movable support base, such as a rotary index table, defining on its upper surface a plurality of identical support pallets, equally spaced apart along the movable support base. Each support pallet is designed to support an array of individual package bases thereon, and is sequentially stopped at spaced positions in the packaging arrangement. At a first position, the packaging arrangement receives blister package bases, each having a product deposited therein, and places the package bases in the support pallet then at the first position. At subsequent positions, the packaging arrangement verifies the presence and alignment of each package base, deposits a fixed dosage of saline solution into each package base, optionally verifies that a fixed dosage of saline solution has been deposited in each package base, places a marked laminated cover over the package bases, heat seals the laminated cover to the package bases, and finally unloads the completed blister packs from the packaging arrangement, for subsequent processing such as sterilization and secondary packaging.
2. Discussion of the Prior Art
The prior art discloses the use of rotary index tables and also linear conveyer arrangements in packaging equipment, the packaging of contact lens in saline solution, and the checking of various packages by a variety of optical probes. Moreover, the prior art also discloses heat sealing lids or covers to container bases, but in the prior art methods of heat sealing, the temperature of the sealing heads are generally maintained at lower temperatures, and the sealing heads are generally applied for longer periods of time as compared with the present invention. In one prior art approach, a pneumatic cylinder presses a heated sealing head against the covers being applied to package bases on a rotary index table, and a microswitch measures when the pneumatic cylinder is at the end of its power stroke, which starts a measured heater timing period. This approach is very inaccurate as the tolerances of all of the components, including the rotary index table, the pneumatic cylinder, and the height of the package and foil in the pallet creates timing problems.
Rather than detecting a particular physical position of the pneumatic press as in the prior art, the present invention measures the force applied by a pneumatic cylinder, and activates a timer when the measured force reaches a threshold force, which is approximately 75% of the maximum force generated by the pneumatic cylinder. Moreover, the present invention positions a support below the rotary index table to ensure that deflections under the pneumatic press are minimized.